This invention relates to a jaw assembly for gripping and releasing objects and is of the type which is used in a machine having a movable arm which operates to grip workpieces at one station, by means of said jaw assembly, transfer the workpieces to another station, and release the workpieces at the latter station.
In order to promote productivity in manufacturing operations, it is often desirable to employ machines which can repetitively execute a cycle of operation to move parts, or workpieces, from one station to another station. These devices are today commonly referred to as robots. As such they may comprise a movable arm mounted on the robot device which is operable to grip a workpiece at one station, move the workpiece to another station, and release it at the latter station.
The actual work-engaging means which is used on a work arm may be either passive (no moving parts in of itself), or it may be active (moving parts). Active work-engaging means of this type are commonly referred to as jaw assemblies. When the arm is in the correct position at one station the jaw assembly is operated to grasp a workpiece or workpieces. It maintains its grasp on the workpiece or workpieces while the work arm transfers it or them to another station. Upon arrival at the other station, the jaw assembly releases the workpiece or workpieces and then returns to the first station to conclude a cycle. This cycle is repeated either continuously or in response to a particular stimulus, depending on the operation involved.
It is important that jaw assemblies be capable of reliably gripping workpieces so that they are not inadvertently or accidentally dropped. Disruptions of this type can defeat the purpose of using robots.
It is also important that the jaw assemblies be operable to provide a suitable gripping force upon workpieces in accordance with the particular nature of the workpieces involved. An especially difficult problem is in gripping workpieces from the side (either an inside or an outside diameter, for example) and then lifting and/or lowering such workpieces by means of the work arm. Prior devices have been beset by different problems, for example, having excessive weight, limited stroke, and being not useful with different shaped workpieces.
The present invention is directed to a jaw assembly which is particularly well suited for application where workpieces are gripped from the side and moved with motion which includes a vertical component. It is effective for use in gripping workpieces at either inside or outside diameters, and it is capable of use with a range of varying diameters. Of particular advantage is that the jaw elements of the jaw assembly which grip a workpiece are mounted in such a manner that increased surface gripping area of the jaw elements with a workpiece is obtainable even though the radial motion which is imparted to the jaw elements is along a component which is arcuate rather than truly linearly radial. In other words, the invention is effective, in the case of gripping a vertical surface of a workpiece, to maintain the work gripping surface of the jaw vertical so as to maximize the surface area at which gripping occurs, yet with the use of a linear actuator (i.e. fluid cylinder) which operates axially of the jaw assembly. The invention can be fabricated with relatively simple mechanism, and provide increased surface gripping area for gripping workpieces of various diameters over a range of diameters within the confines of a dimensionally compact envelope. The invention is also susceptible to various embodiments depending upon the particular requirements for gripping and releasing particular workpieces.
The foregoing features, advantages and benefits of the invention along with additional ones, will be seen in the ensuing description and claims which should be considered in conjunction with the accompanying drawings. The drawings disclose a preferred embodiment of the invention according to the best mode contemplated at the present time in carrying out the invention.